EFFECT OF SHEATH CURVATURE ON RAYLEIGH-TAYLOR MITIGATION IN HIGH-VELOCITY UNIFORM-FILL, Z-PINCH IMPLOSIONS

Recent gas puff experiments on the 7-MA Saturn machine identified a cu rved surface at the plasma-vacuum interface during the run-in phase of the implosion. Incorporating this topology into a corresponding two-d imensional magnetohydrodynamic calculation revealed that this curvatur e plays a surprisingly dominant role in mitigating Rayleigh-Taylor (RT ) growth prior to stagnation. Calculations with both Saturn and repres entative PBFA-Z parameters show that sheath curvature contributes to t he reduction in RT growth by convecting the instability to the edges o f the pinch faster than it can grow.